Speed and Velocity Calculator
Solve for speed, distance, or time using the motion equation v = d / t. Enter any two values and this calculator finds the third, with results shown in several common speed units at once.
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Result
About Speed vs. Velocity
Speed is a scalar quantity — it only has a magnitude, telling you how fast something is moving regardless of direction. Velocity is a vector quantity — it has both a magnitude and a direction (for example, "60 mph north" instead of just "60 mph"). This calculator computes average speed (or the magnitude of average velocity) assuming straight-line motion between a start and end point, using the simple relationship v = d / t. It does not track direction, and it does not model instantaneous speed at any single moment or account for acceleration — for that, an object's speed would need to be measured continuously rather than averaged over a distance and time.
Real-World Speed Reference Values
| Activity / object | Approx. speed |
|---|---|
| Walking | ~1.4 m/s (~3.1 mph) |
| Running | ~3–6 m/s (~6.7–13.4 mph) |
| Car on the highway | ~30 m/s (~65 mph) |
| Commercial jet (cruise) | ~250 m/s (~560 mph) |
| Speed of sound (air, sea level) | ~343 m/s (~767 mph) |
| International Space Station (orbit) | ~7.66 km/s (~17,150 mph) |
How to Use This Calculator
- Select which variable you want to solve for — speed, distance, or time — using the tabs at the top.
- Enter values for the other two variables in their respective fields.
- Choose appropriate units for each input using the dropdowns.
- Click Calculate — or try one of the quick example buttons to pre-fill a real-world scenario.
The result panel shows speed, distance, and time together in SI units, plus the solved (or given) speed converted into m/s, km/h, and mph in one line for quick comparison. This calculator shares the same "rate = amount / time" structure as the Wave Frequency Calculator, which solves v = f × λ instead of v = d / t. Once you know an object's velocity, it becomes a direct input to the Kinetic Energy Calculator (KE = ½mv²). And once you know an object's speed, you can find the force needed to accelerate it with the Force Calculator (F = ma).
Frequently Asked Questions
What's the difference between average speed and instantaneous speed?
Average speed is the total distance traveled divided by the total time taken — that's exactly what this calculator computes. Instantaneous speed is how fast something is moving at one specific moment, like a car's speedometer reading right now. A road trip might have an average speed of 55 mph even though the instantaneous speed varied between 0 mph (stoplights) and 75 mph (highway) along the way.
How do I calculate speed from GPS distance and time?
If a GPS device or running app gives you a distance traveled and the elapsed time, just divide distance by time — the same v = d/t formula this calculator uses. Enter the distance and time it recorded, select "Speed" as the variable to solve for, and choose the units that match your data (for example, kilometers and minutes, or miles and hours).
Why are knots used for ships and aircraft instead of mph or km/h?
A knot is one nautical mile per hour, and a nautical mile (1,852 m) is defined based on one minute of latitude on the Earth's surface. That makes knots directly useful for navigation, since a vessel's speed in knots ties neatly into distances read straight off a nautical chart or GPS coordinates — a convenience that mph and km/h don't offer on the water or in the air.
What does "Mach" speed mean?
Mach number is speed expressed as a multiple of the local speed of sound. At sea level and standard temperature, the speed of sound is about 343 m/s (~767 mph), so Mach 1 ≈ 343 m/s, Mach 2 ≈ 686 m/s, and so on. Because the speed of sound changes with altitude and air temperature, the same aircraft speed in mph can correspond to a different Mach number at different altitudes.
Does this calculator account for acceleration?
No. This calculator assumes constant (or average) speed over the given distance and time — it does not model how an object speeds up or slows down along the way. If you need to work with acceleration or the forces that cause it, the Force Calculator handles Newton's second law (F = ma) directly.
